For unwinding electrical cables and laying them in a trench or channel, it is already known to use hauling gear for the purpose of replacing numerous workers who have to be assigned to this task, when the latter is carried out manually.
As drive means for the cable to be unwound, a relatively old known apparatus comprises an endless rubber belt located under the cable and retractable rollers which press against the upper part of the cable in order to apply the latter against the endless belt (French Pat. No. 1 473 248). The arrangement of the driving device: motor, reduction gearing, pulley for driving the endless belt and auxiliary pulley, is located in the lower part of this apparatus, which has two drawbacks:
on the one hand, the motor as well as other relatively delicate parts are inadequately protected from water, sludge and sand which are generally found at the bottom of trenches;
on the other hand, the arrangement of the driving device located in a lower position, as well as the base supporting this device, prevents direct laying of the unwound cable in the trench or channel intended to receive the latter or also the hauling of several cables in succession, without moving the apparatus. In fact, since the cable emerges through the upper part of the apparatus, it is necessary to place the apparatus off center in the trench for these operations and, to this end, to provide a recess on the side of the trench allowing the movement of the apparatus.
Other more recent apparatus are also known, in which the device for driving the cable to be unwound comprises one or more wheels provided with tires (French Pat. No. 2,259,460 and its Certificate of Addition 2,290,772). In the case of such apparatus also, the drive wheel or wheels are located below the cable, while a retractable pressure roller bears against the upper part of the cable. A frame protects the mechanical components, but this frame rests on the bottom of the trench over a considerable width and one thus encounters the same drawbacks, namely the impossibility of laying a cable which has been pulled along, or unwinding several cables in succession without moving the apparatus sideways.